Being born in parts of US South may up stroke risk

NEW YORK (Reuters Health) - Where you're born could influence your risk of dying from a stroke decades later, new research shows.

Being born in one of the seven southeastern U.S. states making up the "Stroke Belt" increased a person's likelihood of suffering a deadly stroke, whether or not they still lived in one of these states, Dr. M. Maria Glymour of the Harvard School of Public Health in Boston and her colleagues found. And living in one of these states when a person died also boosted the chance that it would be a stroke that was the cause of death.

"Even though stroke is much more common in elderly people than young people," Glymour noted in an E-mail to Reuters Health, "it seems the roots of the disease reach back to early life." The findings suggest, she added, that "to understand and prevent strokes, we will need to start early."

Death from strokes in the Stroke Belt states--North Carolina, South Carolina, Georgia, Tennessee, Arkansas, Mississippi, and Alabama-is higher than it is elsewhere in the US, Glymour and her colleagues point out in Neurology, but the reasons why remain unclear. "This is really a great puzzle," Glymour said. "It has been hard to study this because there are so few data sources available to show this pattern."

She and her colleagues looked at death records for 1980, 1990 and 2000 for US-born black and white men and women 30 to 80 years old to examine how living in the Stroke Belt, or being born there, might influence stroke death risks.

Birth in one of the seven states and residence there at the time of death was independently linked to an increased stroke death risk, Glymour and her team found. While the increased risk was far smaller than the risk seen for established stroke risk factors like high blood pressure or smoking, she noted, the effects on a population level are large.

Put another way, if African Americans born in the Stroke Belt had the same risk as those born outside it, Glymour explained, this would have eliminated about 10% of all fatal strokes suffered by African Americans in 2000.

Whatever's going on in the Stroke Belt doesn't appear to be genetic, according to Glymour, and it is likely to be something that affects everyone-white and black, rich and poor.

The finding that Stroke Belt birth boosts risk suggests that childhood influences may be involved, she added.

These could include "social norms influencing dietary patterns in childhood, the quality of public resources such as the school system, stress pathways relating to community conflict, lifelong access to high quality preventive medical care, or physical risks associated with environmental conditions are plausible possibilities," Glymour explained. "This does not mean these are the reasons, but they are possibilities we need to study."

SOURCE: Neurology, December 1, 2009.

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